The present invention relates to a rigid container for tobacco products.
The invention finds application to particular advantage in the manufacture of hinge-lid cigarette packets fashioned from relative flat precreased and diecut blanks of cardboard or the like, to which reference is made explicitly in the following specification albeit implying no limitation.
The traditional type of rigid packet appears as a parallelepiped of rectangular section with sharp longitudinal corner edges; such a packet presents certain drawbacks deriving from a shape not readily adaptable to the human anatomy, and from the fact that the aforementioned longitudinal corner edges can occasion wear on the pockets of garments worn by the smoker.
These problems have been addressed by the prior art, which offers a rigid packet with longitudinal corner edges presenting a rounded profile that has a radius of curvature matched to that of a single cigarette. In addition to overcoming the drawbacks mentioned above, this type of packet affords the advantage that it can be fashioned from a flat diecut blank of smaller surface area than that of traditional blanks, thus bringing a cost benefit. Nonetheless, it has been found that a packet made in this way still presents certain drawbacks.
A first drawback is that the absence of sharp longitudinal corner edges results in a diminished structural rigidity tending to render the packet easily deformable, especially along the rounded corner edges. Any deformation of the rounded corner edge will impact directly on the single cigarette occupying this same corner of the packet, given that approximately one quarter of the cylindrical surface area presented by the cigarette is breasted with the internal surface presented by the radiused band of material coinciding with each one of the four longitudinal corner edges.
A second drawback is that the rounded corner edges in question can be produced only by making extensive modifications to conventional packer machines. In particular, complex deforming steps are required in order to precrease the areas of the blank that will provide the bands constituting the rounded corner edges on the finished packet.
Another drawback is that traditional cellophaners of the type used to envelop single packets with a sheet of transparent overwrapping material were designed originally to handle parallelepiped packets with sharp longitudinal corner edges. Such overwrapping machines have been found unsuitable for packets of the type referred to here. Most noticeably, surplus material tends to bunch around the top and bottom end faces at the ends of the rounded corner edges, forming unsightly creases and folds which in particular will project from the faces of the packet once the heat seal step has been effected.
The object of the present invention is to fashion a rigid container for tobacco products that will be free of the drawbacks mentioned above.
The stated object is realized according to the present invention in a rigid container for tobacco products appearing prismatic in shape, which comprises a top end face, a bottom end face and a plurality of side faces. At least two mutually adjacent side faces of the container each present a respective flat portion and at least one longitudinal lateral band of curved profile with the concave surface directed inwards, embodied in such a way that the lateral bands of the two adjacent faces are joined one to another along a sharp longitudinal corner edge.